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Overkill of the North American MegafaunaPractice
    1. To argue that modern people have continued to have drastic effects on animal species
    2. To illustrate how people from different historical times treated animals differently
    3. To question the idea that ancient people could have hunted the megafauna to extinction
    4. To emphasize that modern people are more successful hunters than ancient people were
    1. after a period of many years
    2. subsequent to a prediction
    3. from time to time
    4. at the same time and by chance
    1. Climate changes that would have favored human population expansion occurred at the time of the extinctions.
    2. The presence of human hunters had caused animal extinctions in other time periods.
    3. There was a pattern of climate change earlier than 11,000 years ago that had not caused animal extinctions.
    4. Harmful climate changes 11,000 years ago would have required humans to hunt larger numbers of animals for food.
    1. A computer model was designed to determine how long it would have taken for a small group of hunters to spread across North America.
    2. A computer model showed that it was possible for a small group of hunters to spread across North America and kill off game animals in just 300 years.
    3. According to a computer model, people coming into North America 12,000 years ago had to kill game animals in order to feed their population.
    4. According to a computer model, about 12,000 years ago conditions enabled a small group of hunters to enter and cross North America in about 300 years.
    1. Scientists used mathematical models to show that most of the extinctions occurred in areas where humans had recently arrived.
    2. Scientists established that the main population of North Americans who hunted lived in Canada during the time of the megafauna extinctions.
    3. Scientists used numerical models to confirm that a small population of humans could have caused big-game extinctions in a relatively short period of time.
    4. Scientists used statistics to prove beyond doubt the currently accepted view that human hunters were the main cause of the megafauna extinctions.
    1. Agenbroad showed that Mosimann and Martin’s estimates of the amount of time needed to drive big-game to extinction were correct.
    2. Agenbroad’s maps were the first to indicate the ages of the Clovis sites.
    3. Agenbroad reinforced the idea that humans could have caused the extinctions.
    4. Agenbroad’s studies of wooly mammoths led to his discovery of Clovis sites.
    1. accepted the truth of
    2. was unaware of
    3. was troubled by
    4. called attention to
    1. The Clovis sites that contain the remains of mammoths were settled by humans long after the extinctions occurred.
    2. Only a few of the Clovis sites are located near known mammoth habitats.
    3. No archaeological evidence of extinctions has been found at Clovis sites since 1982.
    4. The number of mammoth remains found at Clovis sites is smaller than would be expected if hunting by humans had caused the extinctions.
    1. To show that extinctions occurred in areas other than North America.
    2. To challenge Martin’s claim that the lack of megafauna remains supports his model of the megafauna extinctions.
    3. To identify a country where humans were highly skilled as hunters.
    4. To help explain why it is unclear whether all large herbivores of late Pleistocene America became extinct after the appearance of Clovis.
    1. The rapid rate of the spread of humans explains why the extinctions also occurred at a rapid rate.
    2. The lack of evidence of human-caused extinctions is not surprising in view of the speed with which the extinctions occurred.
    3. It is likely that more evidence will be found as dating methods improve.
    4. If humans did contribute to the extinctions, much more evidence of that would have been found by now.
  1. One possible nonhuman cause—weather cycles—is not consistent with what scientists know about the timing of the extinctions.
  2. About 11,000 years ago, all of North America’s megafauna became extinct.
    1. That the first humans migrated to North America near the same time as the extinctions of the megafauna has led many to believe that hunting by humans was a significant cause of those extinctions.
    2. Support for the hypothesis that hunting by humans caused the extinctions has been provided by computer models, as well as by the discovery of some mammoths’ remains near human settlements.
    3. There is more evidence that human settlers hunted large flightless birds like the moa into extinction than there is that hunters caused the extinction of large mammals like the mammoth.
    4. Early North Americans known as the Clovis society developed spears in order to hunt enough large animals to feed their population as it expanded across vast areas of the continent.
    5. Scientists have proven that the human hunters of large animals who migrated across North America grew in number so quickly that they killed off most of the megafauna within a few hundred years.
    6. Some scholars argue that the evidence linking mammoth remains to human settlements is insufficient to establish that hunting by humans was a significant factor in the megafauna extinctions.